Dehydration



Jan. 1 6, 1940. D. M'CDQNALD bEHYDn-ATION 1937 2 Shets-Sheet 1 Filed April 17,.

Jan. 161940.

D. McDoNALD DEHYDRATIQN Filed April `1'7, 1937 2 Sheets-Sheet 2 i Patented Jan. 16, `19410 uNlrsofsrA'rss PATENT ori-'1er Y aunts,

`Dan ,'MeDonaldDLos Angeles, Calif.; assigner to @Engineering Incorporated. Los Angeles, Calif., a corporation of California Application April 1'1, 1937, serial No. 131,593

1 claim. -(c1. 2oz- 169) This invention relates to apparatus for solventextracting oil from oleaginous material such as garbage, meat scraps, fish, meal and seeds of various kinds, vegetables, fruit, etc., and then freeing residual material of solvent and moisf ture; the apparatus being particularly applicable to the process described and claimed in my copending application Ser. No. 84,849, tiled Jun 12,1936.

It is an object of the invention to employ a dehydrating oil bath in connection with solvent extraction of oil, solvent being employed for first extracting oil from material, with residual material then dehydrated `in the oil bath and the dehydrated material then preferably treated with solvent for extracting any oil which may have been carried over with the`material from`the oil bath. f

It is a still further object of the invention to `distill oil-bearing solvent in the dehydrating oil bath for vaporizing both solvent and aqueous moisture and for replenishing the oil bath by the oil of this distillation process.

It is a still further object -of the invention to preferably employ a solvent having a lower 'latent heat and higher vapor pressure than aqueous moisture, and toipreerably-.maintain the system under partial vacuum and heat the oil bath to a temperature well above the vapor point of the aqueous moisture, whereby'efiicient heat transfer is provided for rapidly and efficiently vaporizing solvent and aqueous moisture, and whereby economical and efiicient recovery of solvent is 'assured.

It is a still further object of the invention to provide a continuousvprocess, with the material passingcontinuously through a solvent-extraction column, with residual material then passing continuously through an oil bath for dehydration and thence being preferably passed through a v receptacle containing -a solvent which extracts oil carried over with'the dehydrated material, and preferably iinally passing continuously through a dryer wherein the last traces of solvent are evaporated and from whence the residual material is continuously discharged.

It is a-still further object of the invention to provide a continuous process, operating under a solvent.

' the valuable oil has` been thus extracted and material whichXhas been dehydrated in the oil bath, is continuously supplied to the extraction chamber and is continuously withdrawn therefrom and discharged into the oil bath for distillation therein, Withthe aqueous and solvent vapors 5 A from the oil bath and the solvent vapors from the dryer continuously withdrawn.4 Further objects of the invention will be readily understood from the following description of the accompanying drawings, in which: 10

Fig. 1 is an apparatus for dehydrating material such as garbage, with both the original oil content and the oil ef the dehydrating process then extracted from the dehydrated material by a suitable solvent.` y l Fig. 2 is an apparatus for solvent extraction` ofl oil from material such as orange peel, with the residual peel then dehydrated and the oil of. the dehydrating process then extracted by a suitable Referring to Fig. ,1, the :material is rst de- 20 hydrated in an oil bath, and then the oil which has been used in the dehydrating process, together with axiy original oil content in the material, is extracted by a suitable solvent. Such process is particularly applicable to dehydration of garbage, iish, animal scraps, etc.

On the other hand, when the material contains a valuable oil, the-recovery of which is of primary importance, e. g. extraction of oil from orange peel, etc., the apparatus shown at Fig. 2 may be' employed, the material being first subjected to a.

suitable extraction process, such as a solvent extraction process, and the material from whichv which residual material it may be desiredl to thoroughly dry, being then dehydrated in an oil bath, with subsequent solvent extraction'of the oil which has been used in the dehydrating process. The oil for the dehydratirig` process may be furnished by the material being dehydrated, e. g. garbage or animal scraps; or material which contains no oil, e. g. vegetables or fruits, or material from which the oil has been .previously` extracted, e. g. orange peel, may be dehydrated, with the oil for the dedhyrating oil bath supplied from any extraneous source. e. g. a suitable mineral oil or a portion of the oil which has been extracted from the material prior to dehydration.

'Ihe apparatus shown at Fig. 1, which does not provide for solvent extraction of oilprior to dehydration and which is particularly applicable for dehydrating garbage, etc., includes a dehydrating chamber I,-.w hich is preferably continuously sup- 6I nrl plied with garbage from `a hopper 2 via a conveyor 3, with heavy inorganic matter which may be present with the garbage, e. g. glass, metal, etc.. removed by gravity at the outlet 4 and carried by a conveyor 5 to a receiver 6. An oil bath 601s maintained in the chamber I, with excess oil overflowing into a stand pipe 32, and with the oil bath maintained at the desired temperature by a steam Jacket 8 which surrounds the lower part of the chamber I to the level of the oil bath.

The garbage is continuously moved'along the chamber I by a spiral conveyor 9 which also disintegrates the garbageto insure gravity discharge of extraneous material at the outlet 4; and a conveyor Il continuously elevates the dehydrated garbage at the exit end of the chamber I and dumps it into an oil extractor which is preferably a U-tube I2--I3 containing a'suitable solvent. The U-tube has spiral conveyors Il-IE in its respective legs, vthe conveyor I4,y moving the del hydrated garbage down the le'g l2 of the extractor tained in the seal above its discharge gate, with,`

and the conveyor I5 then elevating the garbage through the leg I3 of the extractor. The dehydrated garbage fromwhich the solvent has extracted the oil, is discharged from the leg I3 of the extractor into a suitable dryer I3, the material being preferably agitated and moved continuouslyalong the dryer by a spiral conveyor I3, anda steam jacket I1 maintaining the desired temperature for evaporating and removing all remaining traces of the solvent.

The system is preferably a closed system under 4 partial vacuum, with the supply hopper 2 preferably sealed by a body of oil which is shown at 20, and through which the material which is to be treated may be continuously supplied to the system, and with the dehydrated garbage which passes through the dryer continuously discharging via conduit 2| which has a seal 10, preferably of the type disclosed in my copending application Ser. No. 137,884, filed April 19, 1937, and whereby a compact mass of the dried material is mainthis mass of material sealing the conduit 2| to the atmosphere while material is discharging via the gate.

The partial vacuum in the system withdraws vapors from the chamber I at a dome 22 which 4 -communicates with a conduit 23, andthe partial vacuum in the system also withdraws vapors from the dryer IG via a conduit 2.4. The vapors fromthe conduits 23-24 are passed through av .condenser 2i from whencethe condensate is drawn into a water separator 21 via aconduit 23. `Water is drained off at 30, and alconduit 3l .leads from the upper portion of the water sep-- arator to a suitable vacuum pump (not shown) whereby the system is -.maintained under parltial vacuum.v The solvent -which collects in the i water separator is supplied via pipe 29 to the upper end ofthe leg I3 of the oil extractor and overows from the leg I2 'of the oil extractorinto thedehydrating chamberl, thereby flowing through the U-tube I2 I3 counter to the movement of the vmaterial which is being processed.

'The garbagewvhen iirst supplied to the hopper 2 may be passed between rollers 35 which are preferably urged toward one another by-suitable springs sothat they may yield to permit passage of extraneous material such as glass or metal which'the rollers cannot crush, and such extraneous material, which is subsequently collected in the receiver 3, may be periodically removed 7|" therefrom through a normally closed outlet 3l.

`chlorethylene for example.

Any grease or oil settling from the material which is collected in the receiver B may be drained off via a conduit 33. This conduit, and the stand pipe 32 through which excess oil is removed from `the garbage, to which additional oil may be added if necessary in order to create the desired seal vwhen rst starting the dehydrating process; and

ythe conveyor 3 is of a height whereby the vacuum in the system elevates the sealing liquid in this conveyor to a` level short of overflowinto the dehydrating chamber I. The oil bath 6U is maintained by the grease which is a part of the garbage, being replenished during the process as hereinafter described; but Vat the start of the processgrease may be supplied to the chamber I from anyrsitable source in order to initially raise the oil'bath to the desired level.

'I'he oil bath is heated by the steam jacket 8 so as to vaporize the moisture of the garbage which is supplied to the chamber I, and the garbage, when withdrawn via the conveyor II, is thus in a dehydrated condition but may co'ntain some quantity of the oil which has formed the oil bath, together with the grease and oil content of thegarba'ge which has not settled out in the oil bath. This oil and grease is extracted from the dehydrated garbage, preferably by a suitable solvent, such as the chlorinated hydrocarbon solvents, and preferably one of the'- chlorinated hydrocarbon solvents which has a lower latent heat and higher vapor pressure than water, tri- The solvent is supplied via the conduit 29 to the U-tube I 2-I3,

' and ows through the U-tube counter to the direction of movement of the garbage which is being processed, so as to extract oil and grease from the dehydrated garbage. The garbage is then passed through the dryer I6 where any remaining traces of solvent are readily evaporated under the partial vacuum which is maintained in the system, comparatively little heat being required for evaporating the remaining traces of solvent due to the relatively low latent heat of solvents such as trichlorethylene. The dehydrated garbage, free of solvent,l is then continuously withdrawn past the seal 10.

The solvent in the U-tube I2-I3 which has dissolved the oils, fats. and greases of the garbage, is distilled for separate recovery of the 'solvent and the oil, and this distillation is preferably carried on in the dehydrating chamber I,

`WithI thea system under partial vacuum, e. g. I

sol

in tho neighborhood of 26"' no., ino on boon is preferably maintained` at a temperaturev well above the vapor point of the moisture of the garbage, e. g. approximately 200 degrees F., and

the material is maintained inthe oil bath until substantially all of the aqueous moisture has been evaporated. The oil bath thus provides an efficient heat transfer for rapidlyl evaporating aqueous moisture and distilling the oil-bearing solvent, with substantially complete recovery of l solvent assured due to the solvent having a higher partial vacuum in the system, and the solvent; condensate is separated and then` returned to the' U-tube I2-I3 for reuse in4 extracting loil from the dehydrated garbage.` n The apparatus shown at Fig.' 2, which provides `for solvent extraction of oil from material prior to its dehydration, and which is particularly' applicable to processing orange peel, etc., which contains valuable oil, includes a dehydrating chamber la, which is preferably continuously 'supplied'. with material from a hopper Za viaa charging tank Slla. An oil bath 60" is lmaintained in the lchamber I, with excess oil overflowing into a stand pipe 32, and with the oil bath maintained at the desired temperature by a steam jacket 8A ,which surrounds the lower part of the chamberY I to the level of the oil bath. I The material is continuously moved along the 'chamber I alby a spiral conveyor 9*, and a conveyor i Ia'continuously elevates'the dehydrated material-at the exit end of the chamber I'I and `dumps' it into an oil extractor I 2*-I3 which contains a suitable solvent and which is similar material, from which the solvent in the tubes IZB-|38 has extracted oil; is discharged into a dryer I6a which is similar to that shown at Fig. 1, and through which the material is continuously moved. f

The system is preferably a closed system under partial vacuum, with the supply hopper 2'L preferably sealed by a body of` solvent 20* which is `contained in the charging tank 90", and through which the material may -be continuously supplied to the dehydrator I, and with the'dehydi'ated'v material which passes through the dryer' I6* continuously discharging via a conduit 2l* which is provided with a seal 1Il such as previouslydescribed.l 4

` As described in connection with Fig. 1,1the partial vacuum in the system withdraws vapors via conduits 23\-`24`, with the vapors condensed at 25 and the solvent condensate separated at Z-l and drawn oif via conduit 29% 'I'he solvent condensate is preferably collected in a storage tank 80, from whence it is pumped via branch conduits IIIe-82, to the upper portion oi'- the charging tank 90* and to the upper end of the leg I3.of the oil extractor.

'I'he solvent which is supplied to the leg Il? of the oil extractor overflows from theleg I 2 of the extractor, preferably into a conduit Il! by @owing the-oil extractorcounter to movementof the material which is being' proc- 'rho solvent which is supplied via conduit ai" to the charging tank 90, furnishes thevb'ody oi.'

solvent through which the incoming material l passes and which extracts oil from the material;

and the material then rises through the charging.

,aided by a spiral conveyor I, with the solvent which is supplied via conduit IlIl flowing counter to the material so as'to dissolve the last traces of oil `and rinse or displace the oil bearing solvent. 'I'he material from which oil has been extracted by the solvent, then discharges into the dehydrating chamber I". A

n The oil bearing solvent which collects in the bottom of the charging tank 90", is preferably withdrawn .to a still 9|' vla a conduit 92", with the solvent vapors of the distillation process withdrawn via a conduit 83* which leads to the condenser so that the partial vacuum in the system is-maintained in the still, and its solvent vapors are withdrawn, condensed and returned to storage tank 80. The oil from the still is withdrawn via a conduit 94e. This conduit, and the stand pipe 32e through which any'exc'ess oil is removed from the chamber I, may be connected to a conduit 1* through which the oil is with-l rawn to storage. l

.The material from which oil is to be extracted and which is tothenbe dehydrated, is suppliedv at the hopper 2, with oil then extracted by thek solvent 20|,which also forms allquid seal. The

material from'which the oil Ias been extracted is then discharged into the dehydrating chamber I in which the oll'bath 60' lsmaintained by oil supplied from any suitable source. 4 Thematerial which has been dehydrated in the chamber I e and which may contain some quantity of the oil which has formed the bath, is then passed through the extractor Ilm-I3* for extracting this oil, with the material then passing through the dryer I 6* for discharge past the seal 10.

The oil-bearing solvent from the extractor IIL-II", which is returned-to the dehydrating lchamber I'L via the conduit 85e, and any solvent from the charging tank 90| which may have been carried over with 'the material into the dehydrating chamber I, is thus distilled in the dehydrating chamber along with evaporation of aqueousy tank.. preferably by specific gravity differential,

moisture; and thesolvent which is' supplied to' the charging tank 90* andi to the extractor.

I2l-I3'-, is preferably of lower latent heat and higher vapor pressure than water, e. g. tri- I chlorethylene, so that the distillation and de'lis'-,y dration in the chamber Il. will result inV completeV recovery of solvent as previously explained. The

" solvent and aqueous vapors are withdrawn from jected to'an oil extraction process. The material `is dehydrated 'in an oil bath and then subjected to a solvent extraction process whereby oil carried over with the material from the dehydrating bath, together with any original oil content remaining with, the material, is then extracted from the dehydrated material. The solvent is then distilled, preferably in thenoilbath, with all traces of solvent preferably removed from the residual which leadstothe dehydratin'g chamber I, therematerial by evaporation, andY with evaporationjg 4 v memos of vmoisture and of solvent. and distillation of solvent, preferably under I claim:

In exhractic'm apparatus,.means for extraotint oil from material by means of a solvent, a heated oil bath for residual material, a solvent extraction chamber, means for withdrawing material from the oil bath and supplying the same to` the solvent extraction chamber, means for discharging oil-bearing solvent from the suivent extraction chamber to the oil bath, and means for withdrawing vapors from the oil bath.

DAN MCDONALD. 

